Thermoregulator



Dec. 2, 1941- J. SCHWARTZ THERMOREGULATOR Filed Dec.

INVENTOR Joan LEONARD SCHWARTZ 4 ff ATTOR Patented Dec. 2, 1941 THERMOREGULATOR John Leonard Schwartz, Philadelphia, Pa., as-

signor to Philadelphia Thermometer Company, Philadelphia, Pa., a partnership Application December 15, 1939,.Serial No. 309,329

19 Claims.

able to. effect the operation of a given electrical.

circuit as. a function of the variation of a given condition; as for instance conditions of temperature, pressure, density, liquid level, etc. The invention herein relates to devices responsive to any of such conditions, but. for purely illustra.- tive purposes, however, it will be described as it is provided for thermal conditions.

In. the: art of" thermally regulated circuits, a large part of: the field is occupied by thermometers incorporated contacts. in the form of wires extending into the. capillary tube in which a column of mercuryis caused to move by the changes in temperature incident upon the mercury, and which column makes or breaks the contact between the wires. Although it is possible to obtain with those devices control elements which are sensitive to very minute changes in temperatures, measured in, fractions of degrees, yet the sensitivity has certain well defined limits, and the accuracy of the elements is not only merely passably satisfactory, but also varies. during. the life of the instrument.

The factors, involved might be briefly recited for a better understanding of the problem. For responses to small thermal changes. it is necessary to have a large volume of mercury in the bulb, or other housing, communicating with an extremely small capillary or bore in the glass column. Obviously the greater the volume of mercury in. the bulb and the smaller the bore in the glass, the greater the distance the meniscus of the mercury will travel for a given small change in, the temperature to which the bulb is exposed. This has been materially affected by the previous practice of embedding a fine contact wire, such as of platinum or the like, in the glass column in, position to be engaged by the moving mercury column, as this has many disadvantageous and undesirable attributes. It is neces sary to break the glass column, insert the fine wire, and then fuse the severed glass portions and the wire together while trying to maintain the alignment of the bore in each such portion, and this frequently results in a misalignment such as effects a constriction in the bore to vary the flow of mercury through it. The wire must be very fine in order to avoid blocking the bore or passage completely, and it thus cannot carry any appreciable load, and is, of course, possessed in the mercury.

of high resistance. Such wire inevitably effects a partial block of the channel or bore, so as to vary the flow of mercury past it from that occurring in the remainder of the bore. wires used necessitate the use of relays to secure a given power operation. Most undesirable of all, perhaps, is the factor of the contact being made between the moving mercury column and the fixed metal. contact. This latter finds the closing of the circuit through the contact affected by the oxidation or other material floating on the surface of the mercury, either as an incident of past arcing between the mercury and platinum or other wire contact, or because of impurities This changes the resistance factors involved and changes the timing of the circuit making or breaking, and by the erosion or corroding of the wire contacts, due to pitting and the like due to arcing between the mercury and wire, still further changes the timing and resistance involved until through erosion the wire contact disappears and the circuit controlling ceases. The breaking of the circuit of such a device is variable in timing, owing to the fact that the normal surface tension of the mercury tending to pull it away from the contact to form a meniscus on its upper end, is partially nullified by its adhesion to the contact, pursuant to wetting same, so that there is no sharp sudden break, but. only a delayed protracted break which accentuates the arcing and alsov affects the timing of the break, as will be clear.

It is among the objects of this invention: to provide a thermo-regulator which obviates disadvantages attaching to the prior art; to provide a thermo-regulator in which the make and break is through two columns of mercury; to provide a thermo-rcgu1ator responsive to extremely minute changes in condition for sensitive action; to provide a thermo-regulator of extreme accuracy in make and break pursuant to a predetermined change in condition; tov provide a thermally actuated regulator of simplicity and high efliciency; to provide a thermo-regulator wherein the terminals for the controlled circuit enter the respective capillary bores in such a manner as to form a perfect contact without obstructing or otherwise affecting the travel of the mercury; to provide a thermo-regulator wherein the closing of the circuit by the meeting of the two columns of mercury takes place between the juxtaposed edges of the two columns instead of by the complete merging of the menisci of the two columns, as a corollary of which the breaking of the cir- 2 cuit by contraction of the columns gives an in- The finestantaneous circuit break thereby promoting accuracy of operation and greatly increased sensitivity over prior constructions; to provide a novel partition for separating the two columns in the approximate area of contact making; to provide an overflow pocket so arranged and associated with the contact making point of the two mercury columns as to increase the efficiency of operation of the regulator; to provide a novel insulation for the terminal wires of the instrument whereby deleterious action between the mercury and such wires is eliminated; to provide means for bringing the circuit wires to the exterior of the regulator without danger of short circuits developing; and to provide other improvements as will hereinafter appear.

In the accompanying drawing Fig. 1 represents a sectional elevation of a thermo-regulator embodying one form of the present invention; Fig. 2 represents an enlarged sectional detail of the control end of the regulator; Fig. 3 represents a section on line 33 of Fig. 2; Fig. 4 represents a section on line 44 of Fig. 1; Fig. 5 represents a sectional detail on an enlarged scale of the overflow pocket; Fig. 6 represents an elevation of a portion of the control end viewed at ninety degrees from the elevation of Fig. l; and Fig. '7 represents a section on line of Fig. 1.

Referring to the drawing one form of thermoregulator is shown consisting of an elongated glass member ID which is preferably made up of a bulb II, a contact control head l2, and an intermediate neck |3 interconnecting the parts H and I2 and of suitable length to meet conditions of use. The bulb H is formed with a longitudinally disposed partition M which thus divides it into two relatively long chambers I5 and I6 lying side by side and paralleling the axis of the member ID. The neck I3 is an integral extension of the bulb being a glass rod solid except for two capillary through bores and I8 which generally parallel the axis of the neck I3. The bore communicates at one end with the chamber |5 and the bore |8 communicates at one end with the chamber l6. Thus when the respective chambers l5 and I6 are filled with mercury or other temperature responsive medium the two bores l1 and I8 provide channels for columns of mercury rising from the respective bulb chambers and functioning as two thermometers disposed side by side.

The control head |2 forms a receptacle 20 containing a glass post 2| which rises substantially axially from the sealed bottom of the receptacle 20 where it joins the top of the neck l3. This post 2| is provided with two longitudinally disposed capillary channels 22 and 23, the lower ends of which respectively communicate with the bores I1 and I8, and the upper ends thereof terminate at a common level. At this level the body of glass between the channels 22 and 23 is so reduced in thickness as to become a relatively thin partition 25, the upper edge of which is formed with a depressed notch 26 through which the side edge of one mercury column meets the side edge of the other to close the control circuit. In this connection it should be noted that it is extremely important that the bottom of the notch 26 terminates substantially in the horizontal plane which passes through the termination level common to the bores 22 and 23. The common level forms an inlet to an overshoot or expansion chamber, 21 having a laterally turned nozzle 30 terminating in close proximity to the wall of the receptacle 20.

In order to indicate that contact has been made between the two columns of mercury a conductor wire 3| has one end sealed in the post 2| to terminate in the channel 22 while its opposite end is sealed through the wall of the receptacle 20. In a like manner a conductor 32 leads from the channel 23 to the outside of the receptacle 20 at a point preferably axially spaced from the point from which the conductor 3| protrudes. Preferably both conductors 32 and 3| emerge respectively in lateral grooves 33 and 34 formed by a corrugated contour of the extended end of the receptacle 20. The groove 33 seats a conducting strip 35 which is electrically bonded to the conductor 32 and also to a terminal wire 36 leading through the end of a'protective housing 31 for connection to a suitable socket or binding post as the case may be. The groove 34 in like manner seats a strip 38 which is electrically bonded to the conductor 3| and also to a terminal wire 40 leading through the end of the housing 31 in close proximity to the terminal wire 36 so that both wires are convenient for contact with an electrical circuit. The wire 40 forms a connection with a suitable socket or binding post as the case may be for operative association with conductors leading to a suitable indicator. It should be noted that where the two wires 3| and 32 enter the respective channels 22 and 23 the latter are somewhat enlarged in diameter so that contact is always ensured between a wire and the mercury while the wire does not obstruct the travel of the mercury along the channel. Another advantage of this is that as the mercury rises and falls the enlarged channel portions prevent any separation of the mercury in each column caused by entrapped air or gas.

As a means to prevent direct contact between the conductors 3| and 32 and any mercury in the receptacle 2D to thus cause deleterious action, each conductor is encased in a glass sleeve 4| or 42 which is slipped into place and fused to the conductor. Preferably each sleeve terminates just short of the point where it enters the glass to thereby allow sufiicient flexibility for proper bending of the conductors to assembled position. While the glass sleevelike insulation has been found to give excellent results the invention is not limited to this specific insulation as other forms of insulation may be found entirely practical. Obviously the advantageous use of the insulated wires 3| and 32 in the mercury reservoir or chamber may be availed of with the electrode ends terminating in a single column of mercury if this is desired.

For the purpose of anchoring the housing 31 over the end of the control head l2, a length of electric tape 43 or other suitable insulating material is wound about the end portion of the head l2 to cover the terminal wires 35 and. 43 and strips 35 and 38. The housing 31 is anchored to the bulb H by filling one of the circumferential grooves of the corrugated bulb end with a cementitious material 44, such, for example, as litharge as this has been found to give excellent results for uniting the metal housing to the glass.

In the operation of the thermo-regulator it will be assumed that it is to function as a control, or an alarm, or an indicator when the temperature of the test medium reaches, for example, two hundred degrees. The instrument is the reservoir, the settings are made or changed i a manner analogous to earlier devices incorporating' such overflow or overshoot expansion chamber 21. This initial setting or any changes. that may be desired; tube made in the setting th r bov or be ow. the i itial s tting a e accomplished either by first ascertaining the exact difference between the temperature at which the two adjacent columns of mercury have first established lateral contact between them with no excess mercury in the expansion chamber 21', and thetemperature at which the entire expansion chamber is completely filled as a continuation of the mercury columns in the capillary bores. With this information it will obviously be a simple matter to change the temperatures effective upon the bulbs 15 and [6 either to force out undesired mercury, if the initial setting is to be raised above the illustrative 200 setting, or to pick up additional mercury from the surplus in the chamber or reservoir 2!}; as by tilting the instrument and causing the restricted orifice or neck 3B to dip into the mercury, as the temperatune from the bulbs 25 and I6 is lowered as this draws additional mercury into the expansion chamber 2f! to inc arse the amount in the capil laries If thein t ai difierential for the chamber 2'! he -unknown, to the operator he may change the setting by manipulating the instrument at any timethat the. expansion chamber 21 is appreciably less than half filled as. the, entrapped mercury can be shaken from one end of the chamber to the other and then pushed out of the expansion chamber by the globule of en.- trapped mercury-separating gas, or air as the temperature on the bulbs l5 and i5. rises.

The use of the expansion chamber 21 as noted, is analogous to the earlier forms of this particular construction in which two electrodes extend into the same single mercury column.

However the settings are varied it will be appreciated that whatever the selected temperature the regulator is susceptible to insertion into the top of a container with the bulbs l5 and i6, and frequently with the double capillary column l3 as w immersed, in the fluid or liquid, the temperature of which is. to actuate the regulator. The regulator being thussuitably installed is now ready for use and every time. a temperature of the illustrativetwo hundred degrees or other predetermined. setting is reached the circuit including the conductors 3i and 32 is closed by the bridging of the mercuryv from bores H and H3 at the notch 25. In this connection it should be noted that the relatively thin partition with its reeentrant notch ensures an exact meeting of the bores at that point and. avoids the objection present in angularly divergently bored regulators of the. mercury from one bore working over into the other bore to thus introduce erroneous results.

It will be understood that in completing the regulator the upper end of the. bulb portion 62 is left open temporarily until after the mercury is properly disposed in the regulator in order that some inert gas such as nitrogen or hydrogen can be introduced under suitable pressures as to min.- imize both the. effect and the degree of arcing. The open end is then fused and sealed as at E5. to entrap the gas under its pressure.

It isto be und rstood th the. double bored inte ral tube imes e ofany en h fro a inch or so to two or thre e t, f strai ht an l form, without appreciable change of the upper nd ower. portions. a d to e varying depth conditions. so as to secure the suitable exposure of the bulbs I 5. and Hi; to the incident heat conditions It is an important object and feature of this invention. that; the device be adapted particularly for immersion and for successfulimmersed use, to which end all. ofthe wires and electrodes are so housed. or insulated that contact can only be made atthe. extreme end of the instrument. It is noteworthy that this important efiect is produced without proyiding a supplemental shielding envelope about the assembly and especially about the double capillary bore l3, which latter being exposed in non-insulated relation may also contribute to the thermo-responsiveness of the whole.

t is a further important and novel feature of the invention that the extremely thin partition 25*, especially with a notch 26v as shown, secures a ,sensitive constant circuit-closing function and also secures the identical instantaneous certain circuit opening by the knife edge separating function of the partition. The capillary bores 22 and 23. are almost parallel in their extent and the containedcolumns move almost in parallel lines in moving toward and from the thermal circuit regulation point with a minimum of lateral motion.

Another advantageous element of the instant invention lies in the fact that the greatest diameter of the entire, assembly lies in the supporting head so that the. instrument can be inserted into very small apertures and be supported from the tip end in such small apertures, which is a further feature facilitating. the use of the invention in immersion situations.

Having thus described my invention, I claim:

1. In thermorregulators, a section of drawn glass tubing having two parallel bores, the bores at one end merging into' a single channel, bulbs attached to the tubing in communication with the respective bores, mercury in the respective bulbs and bores and forming individual thermometers in a common tubing, electrodes in intimate electrical engagement with the mercury in each thermometer.

2. In thermoaregulators, a section of drawn glass tubing having two parallel independent relatively closely spaced bores extending longitudinally within the boundary surfaces of a common section, each of said bores being enlarged at one end of the section to form a bulb of a thermometer, mercury disposed in each relatively communicating bulb and bore, a bored stem communicating with and common to both bores at the other end of said section to lead them into a single common channel, electrodes in electrical engagement with the mercury of each thermometer.

3. In thermo-regulators, a section of drawn glass tubing having a pair of parallel spaced mercury bores extending longitudinally of the section, the section atone end being enlarged to form bulbs communicating with the respective bores, and at the other end being provided with housing surrounding the common channel and electrodes, and connectors in the housing.

4. In thermo-regulators, a section of drawn glass tubing having two parallel bores, the bores at one end merging into a single channel having an outlet, bulbs attached to the tubing in communication with the respective bores, mercury in the respective bulbs and bores and forming individual thermometers in a common tubing, electrodes in intimate electrical engagement with the mercury in each thermometer, said single channel comprising an enlarged reservoir into which both bores open substantially at their junction point spaced from said outlet.

5. In thermo-regulators, a section of drawn glass tubing having two parallel bores, said tubing reduced at one end whereby the space between the bores is occupied by a thin partition the outer edge of which forms a narrow path across which the menisci of mercury in the bores can spread laterally to establish contact, bulbs attached to the tubing in communication with the respective bores, mercury in the respective bulbs and bores forming individual thermometers in a common tubing, electrodes in electrical engagement with the mercury in each thermometer.

6. In thermo-regulators, two mercury thermometers joined into an integral unit at their upper ends, the said upper ends comprising an integral unit of an enlarged overflow receptacle joining a joint column containing two thermometer bores, said bores separated at the line of jointure of the receptacle by a thin partition forming a narrow transverse path for lateral mutual joining motion of the respective mercury columns of the respective thermometers, and so arranged that the closing of a physical path of mercury across said partition by the rising of the mercury in the said respective bores, is substantially instantly followed by overflow of excess mercury into said receptacle.

7. In thermo-regulators, a section of drawn glass tubing having two parallel bores, said tubing reduced at one end whereby the space between the bores is occupied by a thin partition the outer edge of which has a notch which forms a narrow path across which the menisci of mercury in the bores can spread laterally to establish contact, bulbs attached to the tubing in communication with the respective bores, mercury in the respective bulbs and bores forming individual thermometers in a common tubing, electrodes in electrical engagement with the mercury in each thermometer.

8. A thermo-regulator comprising an elongated member formed by two reservoirs, an upper tubular part, and an intermediate length of drawn glass having two capillary bores communicating respectively with said reservoirs and with said tubular part, mercury in said reservoirs to travel through said bores under applied heat, conducting wires respectively entering said bores for contact with the mercury therein, said wires leading through said tubular part to the exterior thereof, and means at the exit end of said bores for causing juxtaposed side edges of said mercury columns to contact to close a circuit.

9. A thermo-regulator comprising an elongated member formed by two reservoirs, an upper tubular part, and an intermediate length of drawn glass having two capillary bores cornmu nicating respectively with said reservoirs and with said tubular part, mercury in said reservoirs to-travel through said bores under applied heat,

conducting wires respectively entering said bores for contact with the mercury therein, said wires leading through said tubular part to the exterior thereof, and means at the exit end of said bores for causing juxtaposed side edges of said mercury columns to contact to close a circuit prior to the uniting of said mercury columns into a common meniscus.

10. A thermo-reg'ulator comprising an elongated member formed by two reservoirs, an upper tubular part, and an intermediate length of drawn glass having two capillary bores communicating respectively with said reservoirs and with said tubular part, mercury in said reservoirs to travel through said bores under applied heat, conducting wires respectively entering said bores for contact with the mercury therein, said wires leading through said tubular part to the exterior thereof, means at the exit end of said bores for causing juxtaposed side edges of said mercury columns to contact to close a circuit, and means to substantially insulate that portion of said wires in said tubular part from contact with said mercury.

11. A thermo-regulator comprising an elongated member formed by two reservoirs, an upper tubular part, and an intermediate length of drawn glass having two capillary bores communicating respectively with said reservoirs and with said tubular part, mercury in said reservoirs to travel through said bores under applied heat, conducting wires respectively entering said bores for contact with the mercury thereimsaid wires leading through said tubular part to the exterior thereof, said bores being separated by a relatively narrow partition merging into a thin bladelike edge in the plane of the exits of said bores, and means at the exit end of said bores for causing juxtaposed side edges of said mercury columns to contact to close a circuit.

12. A thermo-regulator comprising an elongated member formed by two reservoirs, an up-- per tubular part, and an intermediate length of drawn glass having two capillary bores communicating respectively with said reservoirs and with said tubular part, mercury in said reservoirs to travel through said bores under applied heat, conducting wires respectively entering said bores for contact with the mercury therein, said wires leading through said tubular part to the exterior thereof, said bores being separated by a relatively narrow partition merging into a thin bladelike edge in the plane of the exits of said bores, and a port through said edge to cause juxtaposed side edges of said mercury columns to contact to close a circuit.

13. In thermo-regulators, a drawn glass column containing two parallel capillary bores, bulbs containing mercury and communicating with each bore to form mercury columns, a terminus integral with one end of the column containing two bores separated by a narrow partition having an outer edge forming a narrow path across which mercur in the bores has slight lateral travel to establish contact between the mercury columns, wire electrodes mounted in the terminus in engagement with the respective columns, an overflow chamber mounted on the terminus of enlarged diameter relative to the bores and in such position as to receive mercury rising over the outer edge of the partition, a housing integral with the terminus and the column arranged to house the said electrodes and to receive and support excess mercury initially in the chamber, said electrodes h'aving free ends extending through the housing toward its free end.

14. In thermo-regulators, a column containing two parallel capillary bores, bulbs containing mercury and communicating with each bore to form mercury columns, a terminus integral with one end thereof containing two bores separated by a narrow partition having an outer edge forming a narrow path across which mercury in the bores has slight lateral travel to establish contact between the mercury columns, wire electrodes mounted in the terminus in engagement with the respective columns, an overflow chamber mounted on the terminus to enlarged diameter relative to the bores and in such position as to receive mercury rising over the outer edge of the partition, a housing integral with the terminus and the column arranged to house the said electrodes and to receive and support excess mercury initially in the chamber, said electrodes having free ends extending through the housing toward its free end, and a cap mounted on the free end of the housing for supporting the regulator and having end terminals, and connectors electrically joining the respective electrodes and said terminals.

15. In thermo-regulators, a column containing two parallel capillary bores, bulbs containing mercury and communicating with each bore to form mercury columns, a terminus integral with one end thereof containing two bores separated by a narrow partition having an outer edge forming a narrow path across which mercury in the bores has slight lateral travel to establish contact between the mercury columns, wire electrodes mounted in the terminus in engagement with the respective columns, an overflow chamber mounted on the terminus of enlarged diameter relative to the bores and in such position as to receive mercury rising over the outer edge of the partition, a housing integral with the terminus and the column arranged to house the said electrodes and to receive and support excess mercury initially in the chamber, said electrodes having free ends extending through the housing toward its free end, the free end of said housing having a series of peripheral grooves, metal bands in respective grooves in electrical engagement with said electrodes, a cap on said free end with terminals electrically connected with said bands.

16. In thermo-regulators, a section of drawn glass tubing, a mercury bulb communicating therewith, said tubing having an overflow end, a closed reservoir surrounding the overflow end of the tubing, a pair of electrode wires embedded in the tubing and extending longitudinally within the reservoir through a Wall thereof to termination in electrical engagement with elements external of the reservoir.

17. In thermo-regulators, a section of drawn glass tubing, a mercury bulb communicating therewith, said tubing having an overflow end, a closed reservoir surrounding the overflow end of the tubing, a pair of electrode wires embedded in the tubing and extending longitudinally within the reservoir through a wall thereof to termination in electrical engagement with elements external of the reservoir, and insulation on said wires.

18. In thermo-regulators, a section of drawn glass tubing, a mercury bulb communicating therewith, said tubing having an overflow end, a closed reservoir surrounding the overflow end of the tubing, a pair of electrode wires embedded in the tubing and extending longitudinally within the reservoir through a wall thereof to termination in electrical engagement with elements external of the reservoir, and insulation on said wires, comprising fused glass.

19. In thermo regulators, a glass envelope having a thin median partition dividing the envelope into parallel contiguous mercury bulbs, glass means definin two mercury bores, said glass means merging into the glass envelope with the respective bores in communication with the respective bulbs, and mercury in both bulbs, the bulbs being disposed in such close adjacency that expansion of the mercury in the bulbs incident to heating the envelope is equal in both bulbs and forces the same volume of mercury into both of said bores.

JOHN LEONARD SCHWARTZ. 

